Method for making organic light emitting diode array

ABSTRACT

A method for forming an organic light emitting diode array is provided. A substrate is provided. A plurality of first electrodes is formed on a substrate surface. A patterned mask layer is disposed on the substrate surface to cover the substrate and expose at least a portion of each first electrode. An evaporating source is provided. The evaporating source comprises a carbon nanotube film structure and an organic semiconductor material. The evaporating source is spaced from the plurality of first electrodes. The carbon nanotube film structure is heated to gasify the organic light emitting material and form a plurality of organic light emitting layers on a exposed surface of the plurality of first electrodes. A plurality of second electrodes are formed on a surface of the plurality of organic light emitting layers. The patterned mask layer is removed to form an organic light emitting diode array.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Chinese Patent Application No.201710296657.0, filed on Apr. 28, 2017, the disclosure of which isincorporated herein by reference.

FIELD

The present disclosure relates to a method for making an organic lightemitting diode array.

BACKGROUND

An organic light emitting diode (OLED) is widely researched because theorganic light emitting diode has many advantages, such as low cost,lightweight, flexible, and simple production process. Conventionally, anorganic light emitting layer of organic light emitting diode is formedby vapor deposition method. A large uniform organic light emitting layeris hard to make. In order to form a uniform organic light emittinglayer, it is necessary to form a uniform gaseous vapor depositionmaterial around a substrate. It is difficult to control an atomdiffusion direction of a gaseous vapor deposition material, and most ofthe vapor deposition material can not adhere to the surface of thesubstrate. Thus, a deposition rate of the vapor deposition material islow.

BRIEF DESCRIPTION OF THE DRAWINGS

Implementations of the present technology will now be described, by wayof example only, with reference to the attached figures.

FIG. 1 is a flowchart of one embodiment of a method for forming anorganic light emitting diode array.

FIG. 2 is a schematic view of one embodiment of an apparatus for formingthe organic light emitting diode array.

FIG. 3 is a schematic view of one embodiment of the organic lightemitting diode.

FIG. 4 is a schematic view of one embodiment of a patterned mask layer.

FIG. 5 is a scanning electron microscope (SEM) image of a carbonnanotube film drawn from a carbon nanotube array.

FIG. 6 is a SEM image of a carbon nanotube film structure.

FIG. 7 is a schematic view of another embodiment of the apparatus forforming the organic light emitting diode.

FIG. 8 is a SEM of one embodiment of the evaporating source afterevaporation.

FIG. 9 is a side view of another embodiment of the organic lightemitting diode.

DETAILED DESCRIPTION

The disclosure is illustrated by way of example and not by way oflimitation in the figures of the accompanying drawings in which likereferences indicate similar elements. It should be noted that referencesto “an” or “one” embodiment in this disclosure are not necessarily tothe same embodiment, and such references mean “at least one”.

It will be appreciated that for simplicity and clarity of illustration,where appropriate, reference numerals have been repeated among thedifferent figures to indicate corresponding or analogous elements. Inaddition, numerous specific details are set forth in order to provide athorough understanding of the embodiments described herein. However, itwill be understood by those of ordinary skill in the art that theembodiments described herein can be practiced without these specificdetails. In other instances, methods, procedures, and components havenot been described in detail so as not to obscure the related relevantfeature being described. Also, the description is not to be consideredas limiting the scope of the embodiments described herein. The drawingsare not necessarily to scale, and the proportions of certain parts maybe exaggerated to illustrate details and features of the presentdisclosure better.

The term “comprise” or “comprising” when utilized, means “include orincluding, but not necessarily limited to”; it specifically indicatesopen-ended inclusion or membership in the so-described combination,group, series, and the like.

Referring to FIG. 1 to FIG. 4, a method of forming an organic lightemitting diode array according to one embodiment is provided. Theorganic light emitting diode array is formed in an apparatus 100. Themethod of forming the organic light emitting diode array comprises thefollowing steps:

S10: providing a substrate 210 and forming a plurality of firstelectrodes 220 on a surface of the substrate 210;

S20: disposing a patterned mask layer 260 on a surface of the substrate210 to cover the substrate 210 and expose at least a portion of each ofthe plurality of first electrodes 220;

S30: obtaining an evaporating source 110, wherein the evaporating source110 comprises a carbon nanotube film structure 112 and an organic lightemitting material 114, and the organic light emitting material 114 islocated on a surface of the carbon nanotube film structure 112;

S40: spacing the evaporating source 110 from the plurality of firstelectrodes 220, and inputting an electromagnetic signal or an electricalsignal to heat the carbon nanotube film structure 112 to gasify theorganic light emitting material 114 and form a plurality of organiclight emitting layers 230 on a exposed surface of the plurality of firstelectrodes 220;

S50: forming a plurality of second electrodes 240 on a surface of theplurality of organic light emitting layers 230; and

S60: removing the patterned mask layer 340 to form an organic lightemitting diode array.

The organic light emitting diode array comprises a plurality of organiclight emitting diodes 200. The substrate 210 is an insulating substrate.The substrate 210 can be a hard substrate or a flexible substrate. Thefirst electrode 220 and the second electrode 240 both are conductivelayers. If a light incident surface of the organic light emitting diode200 is a surface of the substrate 210, the substrate 210 can be atransparent substrate, such as a glass substrate, a quartz substrate, atransparent plastic substrate or a resin substrate. The first electrode220 can be a transparent conductive layer or a porous network structure,such as an ITO layer, an FTO layer or a carbon nanotube film. The secondelectrode 240 can be the transparent conductive layer, an opaqueconductive layer or the porous network structure, such as a metal thinfilm, a metal mesh, the ITO layer, the FTO layer or the carbon nanotubefilm. If the light incident surface of the organic light emitting diode200 is a surface of the second electrode 240, the substrate 210 may bean opaque substrate, such as a silicon substrate. The second electrode240 can be the transparent conductive layer or the porous networkstructure, such as the ITO layer, the FTO layer or the carbon nanotubefilm. The first electrode 220 can be the transparent conductive layer,the opaque conductive layer or the porous network structure, such as themetal thin film, the metal mesh, the ITO layer, the FTO layer or thecarbon nanotube film. The first electrode 220 and the second electrode240 can be formed by a conventional method, such as a vapor depositionmethod, a sputtering method or a coating method. In one embodiment, theorganic light emitting material 114 is a material of the organic lightemitting layer 230. In another embodiment, the organic light emittingmaterial 114 is a precursor for forming the organic light emitting layer230, and the precursor reacts to form the material of the organic lightemitting layer 230 during vapor deposition.

The organic light emitting layer 230 is a high molecular polymer or asmall molecule organic compound having high quantum efficiency, goodsemiconductivity, and thermal stability. A molecular weight of the highmolecular polymer is between 10000 and 100000. The high molecularpolymer can be a conductive conjugated polymer or a semiconductorconjugated polymer. A molecular weight of the small molecule organiccompound is between 500 and 20000. The small molecule organic compoundcan be an organic dye. The organic dye has characteristics of strongchemical modification, wide selection range, easy purification and highquantum efficiency. The small molecule organic compound can be a redmaterial. The red material can be selected from the group consisting ofrhodamine dyes, DCM, DCT, DCJT, DCJTB, DCJTI and TPBD. The smallmolecule organic compound can be a green material. The green materialcan be selected from coumarin 6, quinacridone (QA), coronene,naphthalimide. The small molecule organic compound can be a bluematerial. The blue material can be selected from the group consisting ofN-arylbenzimidazoles, and 1,2,4-triazole derivatives (TAZ) anddistyrylarylene. A material of the organic light emitting layer 230 andthe organic light emitting material 114 is not limited to the abovematerial, as long as a gasification temperature of the organic lightemitting material 114 is lower than a gasification temperature of carbonnanotubes and the organic light emitting material 114 does not reactwith carbon during a vapor deposition process. The gasificationtemperature of the organic light emitting material 114 is less than orequal to 300° C. In one embodiment, the organic light emitting material114 is CH₃NH₃PbI₃.

In the step S10, the plurality of first electrodes 220 are located onthe surface of the substrate 210 to form a plurality of organic lightemitting diodes 220 later. The plurality of organic light emittingdiodes 220 forms the organic light emitting diode array. Locations ofthe plurality of organic light emitting diodes 220 on the substrate 210corresponds to locations of the plurality of first electrodes 220 on thesubstrate 210. In one embodiment, the location of each of the pluralityof organic light emitting diodes 220 corresponds to the location of onefirst electrode 220.

Referring to FIG. 4, the patterned mask layer 260 comprises a pluralityof through holes 262. In the step S20, the patterned mask layer 260 islocated on the surface of the substrate 210 to cover the substrate 210,and at least a portion of each of the plurality of first electrodes 220exposes to air by the plurality of through holes 262. In one embodiment,the patterned mask layer 260 covers the substrate 210, and the pluralityof first electrodes 220 expose to air by the plurality of through holes262. Each of the plurality of through holes 262 corresponds to one firstelectrode 220. In one embodiment, a size of the through hole 262 issmaller than a size the first electrode 220, so that the mask layer 260covers at least a portion of the first electrode 210, causing the firstelectrode 220 to be partially exposed outside. In another embodiment,the size of the through hole 262 is the same as the size of the firstelectrode 220, so that the first electrode 210 is completely exposedoutside. Since the patterned mask layer 260 comprises the plurality ofthrough holes 262, the gaseous organic light emitting material 114 isinstantly adhered to the first electrode 220 after passing through thethrough hole 262. Thus, the organic light emitting layer 230 is formedon the exposed surface of the first electrode 220 uncovered by thepatterned mask layer 260. A pattern of the organic light emitting layer230 is corresponding to the required shape and size of the through hole262 of the patterned mask layer 260.

A material of the patterned mask layer 260 may be a metal, such as,stainless steel, aluminum alloy. The size of the through hole 262 andthe size of the first electrode 220 can be selected according to arequired size of the organic light emitting layer 230. In oneembodiment, the size of the through hole 262 is a 500×500 μm² square.The material of the patterned mask layer 260 is stainless steel. In theS20, a patterned stainless steel layer is directly disposed on thesurface of the substrate 210 to cover the substrate 210 and at least aportion of each of the plurality of first electrodes 220.

In the step S30, the carbon nanotube film structure 112 is a carryingstructure for the organic light emitting material 114. The organic lightemitting material 114 is located on a surface of the carbon nanotubefilm structure 112. The carbon nanotube film structure 112 is capable offorming a free-standing structure and can be suspended by supports. Theorganic light emitting material 114 is located on a surface of asuspended carbon nanotube film structure 112. In one embodiment, in thestep S30, two supports 120 are provided. The two supports 120 are spacedfrom each other and located on opposite two ends of the carbon nanotubefilm structure 112. The carbon nanotube film structure 112 is suspendedby the two supports 120. The organic light emitting material 114 islocated on a suspended surface of carbon nanotube film structure 112.

The carbon nanotube film structure 112 comprises a single carbonnanotube film or at least two stacked carbon nanotube films. The carbonnanotube film comprises a plurality of nanotubes. The plurality ofnanotubes are generally parallel to each other and arrangedsubstantially parallel to a surface of the carbon nanotube filmstructure 112. The carbon nanotube film structure 112 has a uniformthickness. The carbon nanotube film can be regarded as a macro membranestructure. In the macro membrane structure, an end of one carbonnanotube is joined to another end of an adjacent carbon nanotubearranged substantially along the same direction by Van der Waalsattractive force. The carbon nanotube film structure 112 and the carbonnanotube film have a macro area and a microscopic area. The macro areadenotes a membrane area of the carbon nanotube film structure 112 or thecarbon nanotube film when the carbon nanotube film structure 112 or thecarbon nanotube film is regarded as a membrane structure. In terms of amicroscopic area, the carbon nanotube film structure 112 or the carbonnanotube film is a network structure having a large number of nanotubesjoined end to end. The microscopic area signifies a surface area of thecarbon nanotubes actually carrying the photoactive material 114.

In one embodiment, the carbon nanotube film is formed by drawing from acarbon nanotube array. This carbon nanotube array is grown on a growthsurface of a substrate by chemical vapor deposition method. The carbonnanotubes in the carbon nanotube array are substantially parallel toeach other and perpendicular to the growth surface of the substrate.Adjacent carbon nanotubes make mutual contact and combine by van derWaals forces. By controlling the growth conditions, the carbon nanotubearray is substantially free of impurities such as amorphous carbon orresidual catalyst metal particles. The carbon nanotube array beingsubstantially free of impurities with carbon nanotubes in close contactwith each other, there is a larger van der Waals forces between adjacentcarbon nanotubes. When carbon nanotube fragments (CNT fragments) aredrawn, adjacent carbon nanotubes are continuously drawn out end to endby van der Waals forces to form a free-standing and uninterruptedmacroscopic carbon nanotube film. The carbon nanotube array made ofcarbon nanotubes drawn end to end is also known as a super-alignedcarbon nanotube array. In order to grow the super-aligned carbonnanotube array, the growth substrate material can be a P-type silicon,an N-type silicon, or a silicon oxide substrate.

The carbon nanotube film includes a plurality of carbon nanotubes thatcan be joined end to end and arranged substantially along the samedirection. Referring to FIG. 5, a majority of carbon nanotubes in thecarbon nanotube film can be oriented along a preferred orientation,meaning that a large number of the carbon nanotubes in the carbonnanotube film are arranged substantially along the same direction. Anend of one carbon nanotube is joined to another end of an adjacentcarbon nanotube arranged substantially along the same direction by Vander Waals attractive force. A small number of the carbon nanotubes arerandomly arranged in the carbon nanotube film and has a small if notnegligible effect on the larger number of the carbon nanotubes in thecarbon nanotube film arranged substantially along the same direction.

More specifically, the carbon nanotube drawn film includes a pluralityof successively oriented carbon nanotube segments joined end-to-end byVan der Waals attractive force therebetween. Each carbon nanotubesegment includes a plurality of carbon nanotubes substantially parallelto each other and joined by Van der Waals attractive force therebetween.The carbon nanotube segments can vary in width, thickness, uniformity,and shape. The carbon nanotubes in the carbon nanotube drawn film arealso substantially oriented along a preferred orientation.

Microscopically, the carbon nanotubes oriented substantially along thesame direction may not be perfectly aligned in a straight line, and somecurve portions may exist. It can be understood that some carbonnanotubes located substantially side by side and oriented along the samedirection in contact with each other cannot be excluded. The carbonnanotube film includes a plurality of gaps between the adjacent carbonnanotubes so that the carbon nanotube film can have better transparencyand higher specific surface area.

The carbon nanotube film is capable of forming a free-standingstructure. The term “free-standing structure” can be defined as astructure that does not require a substrate for support. For example, afree standing structure can sustain the weight of itself when it ishoisted by a portion thereof without any damage to its structuralintegrity. So, if the carbon nanotube drawn film is placed between twoseparate supports, a portion of the carbon nanotube drawn film, not incontact with the two supports, would be suspended between the twosupports and yet maintain film structural integrity. The free-standingstructure of the carbon nanotube drawn film is realized by thesuccessive carbon nanotubes joined end to end by Van der Waalsattractive force.

The carbon nanotube film has a small and uniform thickness in a rangefrom about 0.5 nm to 10 microns. Since the carbon nanotube film drawnfrom the carbon nanotube array can form the free-standing structure onlyby van der Waals forces between the carbon nanotubes, the carbonnanotube film has a large specific surface area. In one embodiment, thespecific surface area of the carbon nanotube film measured by the BETmethod is in a range from about 200 m²/g to 2600 m²/g. A mass per unitarea of the carbon nanotube film is in a range from about 0.01 g/m² toabout 0.1 g/m² (area here refers to the macro area of the carbonnanotube film). In another embodiment, the mass per unit area of thecarbon nanotube film is about 0.05 g/m². Since the carbon nanotube filmhas a minimal thickness and the heat capacity of the carbon nanotube isitself small, the carbon nanotube film has small heat capacity per unitarea. In one embodiment, the heat capacity per unit area of the carbonnanotube film is less than 2×10⁻⁴ J/cm²·K.

The carbon nanotube film structure 112 may include at least two stackedcarbon nanotube films. In one embodiment, a number of layers of thestacked carbon nanotube film is 50 layers or less. In anotherembodiment, the number of layers of the stacked carbon nanotube film is10 layers or less. Additionally, an angle can exist between theorientation of carbon nanotubes in adjacent carbon nanotube films.Adjacent carbon nanotube films can be combined by only Van der Waalsattractive forces therebetween without the need of an adhesive. An anglebetween the aligned directions of the carbon nanotubes in two adjacentcarbon nanotube films can range from about 0 degrees to about 90degrees. In one embodiment, referring to FIG. 6, the carbon nanotubefilm structure 112 includes at least two stacked carbon nanotube films,and the angle between the aligned directions of the carbon nanotubes inthe two adjacent carbon nanotube films is 90 degrees.

In the step S30, the organic light emitting material 114 is located onthe surface of the carbon nanotube film structure 112 by a plurality ofmethods, such as a solution method, a vapor deposition method, a platingmethod or a chemical plating method. The deposition method may bechemical vapor deposition (CVD) method or physical vapor deposition(PVD) method.

A solution method for depositing the organic light emitting material 114on the surface of the carbon nanotube film structure 112 comprises thesteps of: (301) dissolving or uniformly dispersing the organic lightemitting material 114 in a solvent to form a mixture; (302) uniformlycoating the mixture to the carbon nanotube film structure 112 by spraycoating method, spin coating method, or dip coating method; (303)evaporating and drying the solvent to make the organic light emittingmaterial 114 uniformly attach on the surface of the carbon nanotube filmstructure 112. In the step (S301), the mixture can be a solution or adispersion.

When the organic light emitting material 114 comprises a plurality ofmaterials, the plurality of materials can be dissolved in a liquid phasesolvent and mixed with a required ratio in advance, so that theplurality of materials can be disposed on different locations of thecarbon nanotube film structure 112 by the required ratio.

The organic light emitting material 114 is adhered on and coats thesurface of the carbon nanotube film structure 112. Macroscopically, theorganic light emitting material 114 can be seen as a layer formed on atleast one surface of the carbon nanotube film structure 112. In oneembodiment, the organic light emitting material 114 is coated on twosurfaces of the carbon nanotube film structure 112. The organic lightemitting material 114 and the carbon nanotube film structure 112 form acomposite membrane. In one embodiment, a thickness of the compositemembrane is less 100 microns or less. In another embodiment, thethickness of the composite membrane is 5 microns or less. An amount ofthe organic light emitting material 114 carried per unit area of thecarbon nanotube film structure 112 is small. Thus, in microscopic terms,a morphology of the organic light emitting material 114 may be nanoscaleparticles or layers with nanoscale thickness, being attached to a singlecarbon nanotube surface or the surfaces of a few carbon nanotubes. Inone embodiment, the morphology of the organic light emitting material114 is particles. A diameter of the particles is in a range from about 1nanometer to 500 nanometers. In another embodiment, the morphology ofthe organic light emitting material 114 is a layer. A thickness of theorganic light emitting material 114 is in a range from about 1 nanometerto 500 nanometers. The organic light emitting material 114 cancompletely cover and coat a single carbon nanotube for all or part ofits length. The morphology of the organic light emitting material 114coated on the surface of the carbon nanotube film structure 112 isassociated with the amount of the organic light emitting material 114,species of the organic light emitting material 114, a wettingperformance of the carbon nanotubes, and other properties. For example,the organic light emitting material 114 is more likely to be particlewhen the organic light emitting material 114 is not soaked in thesurface of the carbon nanotube. The organic light emitting material 114is more likely to uniformly coat a single carbon nanotube surface toform a continuous layer when the organic light emitting material 114 issoaked in the surface of carbon nanotubes. In addition, when the organiclight emitting material 114 is an organic material having highviscosity, it may form a continuous film on the surface of the carbonnanotube film structure 112. No matter what the morphology of theorganic light emitting material 114 may be, the amount of organic lightemitting material 114 carried by per unit area of the carbon nanotubefilm structure 112 is small. Thus, the electromagnetic signal or theelectrical signal can instantaneously and completely gasify the organiclight emitting material 114. In one embodiment, the organic lightemitting material 114 is completely gasified within 1 second. In anotherembodiment, the organic light emitting material 114 is completelygasified within 10 microseconds. The organic light emitting material 114is uniformly disposed on the surface of the carbon nanotube filmstructure 112 so that different locations of the carbon nanotube filmstructure 112 carry substantially equal amounts of the organic lightemitting material 114.

In the step S40, the evaporating source 110 faces and is spaced from theplurality of first electrodes 220. A distance between the plurality offirst electrodes 220 and the carbon nanotube film structure 112 issubstantially equal. The carbon nanotube film structure 112 issubstantially parallel to the surface of the plurality of firstelectrodes 220. The carbon nanotube film structure 112 coated with theorganic light emitting material 114 faces and is spaced from the surfaceof the plurality of first electrodes 220, and a distance between thecarbon nanotube film structure 112 and the surface of the plurality offirst electrodes 220 is in a range from about 1 micrometer to about 10millimeters. The area of the surface of the plurality of firstelectrodes 220 is equal to or less than the macro area of the carbonnanotube film structure 112. Thus, a gaseous organic light emittingmaterial 114 can reach the depositing surface substantially at the sametime.

The step S40 can be carried out in an atmosphere or in a vacuum. In oneembodiment, the evaporating source 110 and the organic light emittingmaterial 114 are located in a vacuum chamber 130. The electromagneticsignal or the electrical signal is inputted to the carbon nanotube filmstructure 112 to gasify the organic light emitting material 114 and formthe organic light emitting layer 230 on the exposed surface of theplurality of first electrodes 220.

When the electromagnetic signal or the electrical signal is inputted toheat the carbon nanotube film structure 112, the organic light emittingmaterial 114 is rapidly heated to the evaporation or sublimationtemperature. Since per unit area of the carbon nanotube film structure112 carries a small amount of the organic light emitting material 114,all the organic light emitting material 114 may instantly gasify. Thecarbon nanotube film structure 112 and the plurality of first electrodes220 are parallel to and spaced from each other. In one embodiment, thedistance between the plurality of first electrodes 220 and the carbonnanotube film structure 112 is in a range from about 1 micrometer toabout 10 millimeters. Since the distance between the carbon nanotubefilm structure 112 and the surface of the plurality of first electrodes220 is small, a gaseous organic light emitting material 114 evaporatedfrom the carbon nanotube film structure 112 is rapidly attached to theexposed surface of the plurality of first electrodes 220 to form theplurality of organic light emitting layers 230. The area of the exposedsurface of the plurality of first electrodes 220 is equal or less thanthe macro area of the carbon nanotube film structure 112. The carbonnanotube film structure 112 can completely cover the exposed surface ofthe plurality of first electrodes 220. Thus, the organic light emittingmaterial 114 is evaporated to the exposed surface of the plurality offirst electrodes 220 as a correspondence to the carbon nanotube filmstructure 112 to form the plurality of organic light emitting layers230. Since the organic light emitting material 114 is uniformly carriedby the carbon nanotube film structure 112, the plurality of organiclight emitting layers 230 is also a uniform structure. When the organiclight emitting material 114 comprises the plurality of materials, aproportion of the plurality of materials is same in different locationsof the carbon nanotube film structure 112. Thus, the plurality ofmaterials still has same proportion in the gaseous organic lightemitting material 114, and each of the organic light emitting layer 230can be uniform.

The electromagnetic signal can be inputted to the carbon nanotube filmstructure 112 by an electromagnetic signal input device 140. Theelectromagnetic signal input device 140 can be located in the vacuumchamber 130 or outside the vacuum chamber 130, as long as an emittedelectromagnetic signal can be transmitted to the carbon nanotube filmstructure 112. An average power density of the electromagnetic signal isin a range from about 100 mW/mm² to 20 W/mm². Since the structure of thecarbon nanotube film structure 112 has the large specific surface area,the carbon nanotube film structure 112 can quickly exchange heat withsurrounding medium, and heat signals generated by the carbon nanotubefilm structure 112 can quickly heat the organic light emitting material114. Since the amount of the organic light emitting material 114 locatedon per unit macro area of the carbon nanotube film structure 112 issmall, the organic light emitting material 114 can be completelygasified instantly by the heat signals.

Referring FIG. 7, the electrical signal can be inputted to the carbonnanotube film structure 112 by a first electrical signal input electrode150 and a second electrical signal input electrode 152. The firstelectrical signal input electrode 150 and the second electrical signalinput electrode 152 are spaced from each other and electricallyconnected with the carbon nanotube film structure 112. In oneembodiment, the carbon nanotube film structure 112 is suspended by thefirst electrical signal input electrode 150 and the second electricalsignal input electrode 152. The carbon nanotube film structure 112 is aresistive element. The carbon nanotube film structure 112 has the smallheat capacity per unit area and has the large specific surface area butthe minimal thickness. In one embodiment, the heat capacity per unitarea of the carbon nanotube film structure 112 is less than 2×10⁻⁴J/cm²·K. In another embodiment, the heat capacity per unit area of thecarbon nanotube film structure 112 is less than 1.7×10⁻⁶ J/cm²·K. Thespecific surface area of the carbon nanotube film structure 112 islarger than 200 m²/g. The thickness of the carbon nanotube filmstructure 112 is less than 100 micrometers. The first electrical signalinput electrode 150 and the second electrical signal input electrode 152input the electrical signal to the carbon nanotube film structure 112.Since the carbon nanotube film structure 112 has the small heat capacityper unit area, the carbon nanotube film structure 112 can convertelectrical energy to heat quickly, and a temperature of the carbonnanotube film structure 112 can rise rapidly. Since the carbon nanotubefilm structure 112 has the large specific surface area and is very thin,the carbon nanotube film structure 112 can rapidly transfer heat to theorganic light emitting material 114. The organic light emitting material114 is rapidly heated to the evaporation or sublimation temperature.

The first electrical signal input electrode 150 and the secondelectrical signal input electrode 152 are electrically connected withthe carbon nanotube film structure 112. In one embodiment, the firstelectrical signal input electrode 150 and the second electrical signalinput electrode 152 are directly located on the surface of the carbonnanotube film structure 112. The first electrical signal input electrode150 and the second electrical signal input electrode 152 can input acurrent to the carbon nanotube film structure 112. The first electricalsignal input electrode 150 and the second electrical signal inputelectrode 152 are spaced from each other and located at either end ofthe carbon nanotube film structure 112.

In one embodiment, the plurality of carbon nanotubes in the carbonnanotube film structure 112 extends from the first electrical signalinput electrode 150 to the second electrical signal input electrode 152.When the carbon nanotube film structure 112 consists of one carbonnanotube film, or of at least two films stacked along a same direction(i.e., the carbon nanotubes in different carbon nanotube films beingarranged in a same direction and parallel to each other), the pluralityof carbon nanotubes of the carbon nanotube film structure 112 extendfrom the first electrical signal input electrode 150 to the secondelectrical signal input electrode 152. In one embodiment, the firstelectrical signal input electrode 150 and the second electrical signalinput electrode 152 are linear structures and are perpendicular toextended directions of the carbon nanotubes of at least one carbonnanotube film in the carbon nanotube film structure 112. In oneembodiment, the first electrical signal input electrode 150 and thesecond electrical signal input electrode 152 are same as a length of thecarbon nanotube film structure 112, the first electrical signal inputelectrode 150 and the second electrical signal input electrode 152 thusextending from one end of the carbon nanotube film structure 112 to theother end. Thus, each of the first electrical signal input electrode 150and the second electrical signal input electrode 152 is connected withtwo ends of the carbon nanotube film structure 112.

The carbon nanotube film structure 112 is the free-standing structureand can be suspended by the first electrical signal input electrode 150and the second electrical signal input electrode 152. In one embodiment,the first electrical signal input electrode 150 and the secondelectrical signal input electrode 152 have sufficient strength tosupport the carbon nanotube film structure 112, and the two supports 120can be omitted. The first electrical signal input electrode 150 and thesecond electrical signal input electrode 152 can be a conductive wire orconductive rod.

In the step S40, the electrical signal is inputted to the carbonnanotube film structure 112 through the first electrical signal inputelectrode 150 and the second electrical signal input electrode 152. Whenthe electric signal is a direct current signal, the first electricalsignal input electrode 150 and the second electrical signal inputelectrode 152 are respectively electrically connected to a positive anda negative of a direct current source. The direct current power inputsthe direct current signal to the carbon nanotube film structure 112through the first electrical signal input electrode 150 and the secondelectrical signal input electrode 152. When the electrical signal is analternating current signal, the first electrical signal input electrode150 is electrically connected to an alternating current source, and thesecond electrical signal input electrode 152 is connected to earth. Thetemperature of the carbon nanotube film structure 112 can reach thegasification temperature of the organic light emitting material 114 byinputting an electrical signal power to the evaporating source 110. Theelectrical signal power can be calculated according to the formula σT⁴S.Wherein σ represents Stefan-Boltzmann constant; T represents thegasification temperature of the organic light emitting material 114, andS represents the macro area of the carbon nanotube film structure 112.The larger the macro area of the carbon nanotube film structure 112 andthe higher the gasification temperature of the organic light emittingmaterial 114, the greater the electrical signal power. Since the carbonnanotube film structure 112 has the small heat capacity per unit area,the carbon nanotube film structure 112 can quickly generate a thermalresponse to raise the temperature. Since the carbon nanotube filmstructure 112 has the large specific surface area, the carbon nanotubefilm structure 112 can quickly exchange heat with surrounding medium,and heat signals generated by the carbon nanotube film structure 112 canquickly heat the organic light emitting material 114. Since the amountof the organic light emitting material 114 disposed on per unit macroarea of the carbon nanotube film structure 112 is small, the organiclight emitting material 114 can be completely gasified instantly by theheat signals.

FIG. 8 shows a structure of the evaporating source 110 after vacuumevaporation. After evaporating the organic light emitting material 114located on the surface structure of the carbon nanotube film structure112, the carbon nanotube film structure 112 retains an original networkstructure, and the carbon nanotubes of the carbon nanotube filmstructure 112 are still joined end to end.

In one embodiment, the plurality of organic light emitting layers 230with different colors can be formed to form an OLED display. Theplurality of evaporating sources 110 can comprise a plurality of organiclight emitting materials 114. The plurality of organic light emittingmaterials 114 can be formed by different materials with differentcolors. Each of the plurality of through holes 262 of the patterned masklayer 262 corresponds to one organic light emitting material 114. Thus,the plurality of organic light emitting layers 230 can be formed havingdifferent colors.

Referring FIG. 9, in one embodiment, the organic light emitting diode200 comprises the substrate 210, the first electrode 220, a holeinjection layer 252, a hole transport layer 250, the organic lightemitting layer 230, an electron transport layer 254, an electroninjection layer 256, and the second electrode 240. The hole injectionlayer 252, the hole transport layer 250, the electron transport layer254, and the electron injection layer 256 are selectable structures.

In one embodiment, the method for forming the organic light emittingdiode 200 can further comprise a step of forming the hole transportlayer 250 on the surface of the first electrode 220 after the step S30and before the step S40. A method of forming the hole transport layer250 can be a conventional vapor deposition and mask etching method, aspraying method, an ink jet printing method, or the same as the methodof forming the organic light emitting layer 230.

In one embodiment, the method of forming the hole transport layer 250 isthe same as the method of forming the organic light emitting layer 230.The method of forming the hole transport layer 250 comprises steps of:

T1: providing a hole transport evaporating source, wherein the holetransport evaporating source comprises the carbon nanotube filmstructure 112 and a hole transport layer material, and the holetransport layer material is located on the surface of the carbonnanotube film structure 112; and

T2: spacing the hole transport evaporating source from the firstelectrode 220, and inputting an electromagnetic signal or an electricalsignal to heat the carbon nanotube film structure 112 to gasify the holetransport layer material and form the hole transport layer 250 on thesurface of the first electrode 220.

In one embodiment, the method for forming the organic light emittingdiode 200 can further comprise a step of forming the hole injectionlayer 252 between the surface of the first electrode 220 and the holetransport layer 250 after the step S30 and before the step S40. A methodof forming the hole injection layer 252 can be a conventional vapordeposition and mask etching method, a spraying method, an ink jetprinting method, or the same as the method of forming the organic lightemitting layer 230.

In one embodiment, the method of forming the hole injection layer 252 isthe same as the method of forming the organic light emitting layer 230.The method of forming the hole injection layer 252 comprises steps of:

N1: providing a hole injection evaporating source, wherein the holeinjection evaporating source comprises the carbon nanotube filmstructure 112 and a hole injection layer material, and the holeinjection layer material is located on the surface of the carbonnanotube film structure 112; and

N2: spacing the hole injection evaporating source from the firstelectrode 220, and inputting an electromagnetic signal or an electricalsignal to heat the carbon nanotube film structure 112 to gasify the holeinjection layer material and form the hole injection layer 252 on thesurface of the first electrode 220.

In one embodiment, the method for forming the organic light emittingdiode 200 can further comprise a step of forming the electron transportlayer 254 on the surface of the organic light emitting 230 after thestep S40 and before the step S50. A method of forming the electrontransport layer 254 can be a conventional vapor deposition and masketching method, a spraying method, an ink jet printing method, or thesame as the method of forming the organic light emitting layer 230.

In one embodiment, the method of forming the electron transport n layer254 is the same as the method of forming the organic light emittinglayers 230. The method of forming the electron transport layer 254comprises steps of:

M1: providing an electron transport evaporating source, wherein theelectron transport evaporating source comprises the carbon nanotube filmstructure 112 and an electron transport layer material, and the electrontransport layer material is located on the surface of the carbonnanotube film structure 112; and

M2: spacing the electron transport evaporating source from the organiclight emitting layer 230, and inputting an electromagnetic signal or anelectrical signal to heat the carbon nanotube film structure 112 togasify the electron transport layer material and form the electrontransport layer 254 on the surface of the organic light emitting layer230.

In one embodiment, the method for forming the organic light emittingdiode 200 can further comprise a step of forming the electron injectionlayer 256 on a surface of the hole the electron transport layer 254after the step S40 and before the step S50. A method of forming theelectron injection layer 256 can be a conventional vapor deposition andmask etching method, a spraying method, or an ink jet printing method.

A material of the hole transport layer 250 and the hole transport layermaterial may have a strong hole transporting ability. The material ofthe hole transport layer 250 and the hole transport layer material canbe NPB (N, N′-bis-(1-naphthyl)-N, N′-diphenyl-1,4-diamine), TPD (N,N′-diphenyl-N, N′-bis (m-methylphenyl)-1, Biphenyl-4,4′-diamine), orMTDATA (4,4′, 4″-tris(3-methylphenylaniline)triphenylamine).

A material of the hole injection layer 252 and the hole injection layermaterial can be copper phthalocyanine (CuPc) or PEDOT: PSS. The PEDOT isa polymerization of EDOT (3,4-ethylenedioxythiophene monomer). The PSSis polystyrene sulfonate.

A material of the electron transport layer 254 and the electrontransport layer material can be an aromatic compound having a largeconjugated plane, such as, AlQ (8-Hydroxyquinoline aluminum salt), PBD,Beq₂ or DPVBi (4,4′-Bis(2,2-diphenylvinyl)-1,1′-biphenyl).

A material of the electron injecting layer 256 is an alkali metal or analkali metal compound having a low work function. The material of theelectron injecting layer 256 can be lithium fluoride (LiF), calcium(Ca), or magnesium (Mg).

A plurality of organic material layers can be formed on the substrate210 by changing a material carried on the carbon nanotube film structure112 and repeating the S40 many times.

In the step S60, removing the patterned mask layer 260 to form theorganic light emitting diode array. In one embodiment, the material ofthe patterned mask layer 260 is stainless steel.

The carbon nanotube film is free-standing structure and used to carry anorganic light emitting material. The carbon nanotube film has a largespecific surface area and good uniformity so that the organic lightemitting material carried by the carbon nanotube film can uniformlydistribute on the carbon nanotube film before evaporation. The carbonnanotube film can be heated instantaneously. Thus, the organic lightemitting material can be completely gasified in a short time to form auniform gaseous organic light emitting material, and the uniform gaseousorganic light emitting material can be uniformly distributed over alarge area. The distance between the depositing substrate and the carbonnanotube film is small. Thus, the organic light emitting materialcarried on the carbon nanotube film can be substantially utilized tosave the organic light emitting material and improve the depositionrate. The patterned mask layer covers the substrate and exposes at leasta portion of a plurality of first electrodes, and then a plurality oforganic light emitting layers and a plurality of second electrodes aresequentially formed on the plurality of first electrodes, and finallythe patterned mask layer is removed to form a plurality of organic lightemitting diodes at one time. Thus, the efficiency of forming the organiclight emitting diode is improved.

Even though numerous characteristics and advantages of certain inventiveembodiments have been set out in the foregoing description, togetherwith details of the structures and functions of the embodiments, thedisclosure is illustrative only. Changes may be made in detail,especially in matters of arrangement of parts, within the principles ofthe present disclosure to the full extent indicated by the broad generalmeaning of the terms in which the appended claims are expressed.

Depending on the embodiment, certain of the steps of methods describedmay be removed, others may be added, and the sequence of steps may bealtered. It is also to be understood that the description and the claimsdrawn to a method may comprise some indication in reference to certainsteps. However, the indication used is only to be viewed foridentification purposes and not as a suggestion as to an order for thesteps.

The embodiments shown and described above are only examples. Even thoughnumerous characteristics and advantages of the present technology havebeen set forth in the foregoing description, together with details ofthe structure and function of the present disclosure, the disclosure isillustrative only, and changes may be made in the detail, especially inmatters of shape, size and arrangement of the parts within theprinciples of the present disclosure up to, and including the fullextent established by the broad general meaning of the terms used in theclaims. It will, therefore, be appreciated that the embodimentsdescribed above may be modified within the scope of the claims.

What is claimed is:
 1. A method of forming an organic light emittingdiode array comprising: S1: providing a substrate and forming aplurality of first electrodes on a substrate surface; S2: disposing apatterned mask layer on the substrate surface to cover the substrate andexpose at least a portion of each of the plurality of first electrodes;S3: obtaining an evaporating source, wherein the evaporating sourcecomprises a carbon nanotube film structure and an organic light emittingmaterial, and the organic light emitting material is located on a carbonnanotube film structure surface, wherein a heat capacity per unit areaof the carbon nanotube film structure is less than 2×10⁻⁴ J/cm²·K; S4:spacing the evaporating source from the plurality of first electrodes,and heating the carbon nanotube film structure to gasify the organiclight emitting material and forming a plurality of organic lightemitting layers on a exposed surface of the plurality of firstelectrodes; S5: forming a plurality of second electrodes on a surface ofthe plurality of organic light emitting layers; and S6: removing thepatterned mask layer to form an organic light emitting diode array. 2.The method of claim 1, wherein the organic light emitting material isdeposited on the carbon nanotube film structure surface by a solutionmethod, a vapor deposition method, a plating method or a chemicalplating method.
 3. The method of claim 1, wherein the organic lightemitting material is deposited on the carbon nanotube film structuresurface by a solution method, the solution method for depositing theorganic light emitting material on the carbon nanotube film structuresurface comprising: S31, dispersing the organic light emitting materialin a solvent to form a mixture; S32, coating the mixture to the carbonnanotube film structure; S33, drying the solvent to make the organiclight emitting material uniformly form on the carbon nanotube filmstructure surface.
 4. The method of claim 1, wherein the organic lightemitting material comprises a plurality of materials, and the pluralityof materials are dissolved in a liquid phase solvent and mixed with eachother.
 5. The method of claim 1, wherein in the step S4, the evaporatingsource and the organic light emitting material are located in a vacuumchamber.
 6. The method of claim 1, wherein in the step S4, anelectromagnetic signal is inputted to heat the carbon nanotube filmstructure via an electromagnetic signal input device.
 7. The method ofclaim 1, wherein in the step S4, an electrical signal is inputted toheat the carbon nanotube film structure by a first electrical signalinput electrode and a second electrical signal input electrode.
 8. Themethod of claim 1, wherein a distance between the exposed surface of theplurality of first electrodes and the carbon nanotube film structure isin a range from about 1 micrometer to about 10 millimeters.
 9. Themethod of claim 1, wherein the evaporating source comprises a pluralityof organic light emitting materials with different colors.
 10. Themethod of claim 1, wherein a specific surface area of the carbonnanotube film structure is larger than 200 m²/g.
 11. The method of claim1, wherein the carbon nanotube film structure comprises at least onecarbon nanotube film, and the at least one carbon nanotube filmcomprises a plurality of nanotubes joined end to end by Van der Waalsattractive force.
 12. The method of claim 1, wherein the organic lightemitting material is CH₃NH₃PbI₃.
 13. The method of claim 1, wherein thepatterned mask layer comprises a plurality of through holes.
 14. Themethod of claim 13, wherein a pattern of each of the plurality oforganic light emitting layers is corresponding to required shapes andsizes of the plurality of through holes of the patterned mask layer. 15.The method of claim 1, further comprising a step of forming a pluralityof hole transport layers on the exposed surface of the plurality offirst electrodes after the step S3 and before the step S4.
 16. Themethod of claim 15, further comprising a step of forming a plurality ofhole injection layers between the plurality of first electrodes and theplurality of hole transport layers after the step S30 and before thestep S40.
 17. The method of claim 1, further comprising a step offorming a plurality of electron transport layers on a surface of theplurality of organic light emitting layers after the step S4 and beforethe step S5.
 18. The method of claim 17, further comprising a step offorming a plurality of electron injection layers on a surface of theplurality of hole the electron transport layers after the step S4 andbefore the step S5.
 19. The method of claim 1, wherein the carbonnanotube film structure is a free-standing structure and used to carrythe organic light emitting material.
 20. The method of claim 1, whereinthe carbon nanotube film structure is suspended by supports.